The big heatwave: from Algeria to the Arctic. But what's the cause?

Our hemisphere is having a baking summer - and it's not just down to climate changeLast week, authorities in Sweden took an unusual step. They issued an appeal for international aid to help them tackle an epidemic of wildfires that has spread across the nation over the past few days.After months without rain, followed by weeks of soaring temperatures, the nation's forests had become tinderboxes. Continue reading...